The present invention relates to the application of Petri nets to document workflow systems and methods, and more particularly, to active document controlled refinement workflow systems and methods.
A Petri net is a computer science structure that defines a concurrent process. Petri nets may be depicted graphically. In a Petri net, operations are represented by transitions (boxes), and states are represented as places (circles). The causal flow of a token through a Petri net is depicted by arcs linking transitions to states and states to transitions. The status of a state is indicated by the presence or absence of a token at that state.
A document workflow system is a pre-defined set of operations performed on document. A Petri net may be used to represent a document workflow system. In a Petri net representation of a document workflow system, a token passing through the Petri net represents a document. Petri nets provide a unifying formal language for document workflow systems. Typically, in document workflow systems, operations are performed on documents. For example, a document can be encrypted, translated, or photocopied. In a Petri net representation of a document workflow system, operations are represented by transitions.
In traditional document workflow systems, the designer of the document workflow retains absolute control over the workflow process by creating a set of operations that can be performed on a document. In a Petri net representation of a such a traditional document workflow system, the states and transitions in the Petri net are connected together in a fixed way that is predefined by the document workflow designer. Thus, each state and transition in the Petri net representation is pre-defined by design and cannot be changed without redesigning the document workflow system.
It may be desirable to modify the set of operations performed on a particular document in a document workflow system. In a Petri net representation of a prior art document workflow system, a workflow designer can modify a target Petri net by inserting a refinement network into the target Petri net.
The workflow designer specifies the target Petri network. A designer also specifies a refinement network. In prior art systems, the only way to modify the target network is for a workflow system designer to replace part of the target net with a refinement network that is specified by the workflow system designer. Thus, if one desires to perform different operations on each document, the workflow designer has to alter or refine the document workflow explicitly each time for each document.